1. Field of the Invention
The present invention relates to an inductive-type thin-film magnetic head and a magnetic storage apparatus using the magnetic head.
2. Description of the Prior Art
Recently, the recording density of a hard disk drive has been remarkably improved. A recording density after 1990 tends to rise at an annual rate of approx. 60%. To improve the recording density of a hard disk drive, it is preferable to improve the recording track density by decreasing the track width of a magnetic head. Moreover, to improve the recording density, improvement of the recording bit density is similarly important. To improve the recording bit density, it is preferable to increase the resistance to applied magnetic force (Hc) of a magnetic storage medium. Moreover, to write data in a magnetic storage medium having a high Hc, it is preferable to use an inductive recording head having a high recording capacity. Furthermore, to efficiently detect a signal from micro-scaled recording bits, it is preferable to use an MR reproducing head. Therefore, an MR-inductive composite-type thin-film magnetic head obtained by combining an MR reproducing head with an inductive recording head is prospective for high-density recording.
FIG. 19 is a sectional view of a conventional thinfilm magnetic head. The conventional thin-film magnetic head will be hereafter described by referring to FIG. 19.
A conventional thin-film magnetic head 70 is constituted by laminating a lower shielding layer 74, a read gap layer 80 holding an MR magnetosensitive element 78 in an ABS plane 76, a common pole layer 82 serving as an upper shielding layer and a lower pole layer, and a write gap layer 84 in order on an insulating substrate 72, then laminating a first flattening layer 86, a coil pattern layer 88, and a second flattening layer 90 in order on the write gap layer 84 excluding the vicinity of the ABS plane 76, and by laminating an upper pole layer 92 on the write gap layer 84, first flattening layer 86, and second flattening 90 nearby the ABS plane 76.
The common pole layer 82 serves as an upper shielding layer for improving the reproducing resolution of an MR reproducing head and a lower pole layer of an inductive recording head. The MR magnetosensitive element 78 detects a signal magnetic field from a not-illustrated magnetic storage medium facing the ABS plane 76. The thickness of the write gap layer 84 serves as the gap of the inductive recording head. The first flattening layer 86 serves as the insulating base of the coil pattern layer 88 and the second flattening layer 90 corrects the irregular height difference in the coil pattern layer 88. The portion free from the first flattening layer 86 on the write gap layer 84 nearby the ABS plane 76 specifies the gap depth D of the inductive recording head. The recording track width is determined by the front end portion width W (not illustrated) of the upper pole layer 92. The front end portion width W represents the width of the upper pole layer 92 on the ABS plane (front end) in the direction vertical to a drawing surface, which is illustrated in FIG. 2 and the like.
To improve the recording capacity under high-density recording, it is preferable to decrease the gap depth D to 1 xcexcm or less. Moreover, to correspond to high-density recording, it is preferable to realize the upper pole layer 92 having a minimum front end portion width W.
Furthermore, an invention for improving the recording density is disclosed in the official gazette of Japanese Patent Application Laid-Open No. 9-305930. This invention attains its object by using a magnetic recording/reproducing head configured by superimposing a sealed-type MR head on an inductive-type magnetic recording head and thereby, improving the accuracy of widths of the recording coil and recording track of an upper recording head.
To form a necessary gap depth D, it is preferable to form the first flattening layer 86 considerably nearing the ABS plane 76 side, determining the gap depth D. Therefore, the conventional thin-filmmagnetic head 70 has the following problem when forming a resist frame pattern (not illustrated) for forming the upper pole layer 92 through the frame plating method.
The first flattening layer 86, coil pattern layer 88, and the second flattening layer 90 are successively superimposed and then, a resist frame pattern is formed. In this case, a large height difference is formed between the write gap layer 84 and the second flattening layer 90 at the front end portion. Therefore, the thickness of the resist film of the resist frame pattern at the front end portion reaches 10 xcexcm or more. Moreover, the front end of the first flattening layer 86 is formed into a curved surface. Therefore, when light for exposure reflects on the curved surface, the resist frame pattern could easily be overexposed.
Thus, the resist frame pattern for forming the front end portion of the upper pole layer 92 tends to have a large film thickness and it is easily overexposed. Therefore, obtaining a necessary gap depth D makes it difficult to obtain a necessary front-end portion width W.
Therefore, it is an object of the present invention to provide a thin-film magnetic head capable of accurately decreasing a gap depth D and a front-end portion width W and a magnetic storage apparatus using the magnetic head.
The thin-film magnetic head in claim 1 of the present invention is constituted by laminating a write gap layer on a lower pole layer, forming a first flattening layer, a coil pattern layer, and a second flattening layer in order on the write gap layer excluding an ABS plane, and forming an upper pole layer on the write gap layer at least at near the ABS plane. Moreover, a concave portion is formed on the lower pole layer at a position separated from the ABS plane, the concave portion is filled with a non magnetic body, and the gap depth between the upper pole layer and the lower pole layer is determined by the concave portion.
The gap depth is not determined by the distance from the ABS plane to the front end of the first flattening layer but it is determined by the distance from the ABS plane to the margin of the concave portion. Since the concave portion is formed on a flat lower pole layer, no problem occurs in the photolithography process for forming the concave portion. Moreover, the resist frame pattern for forming the front end portion of the upper pole layer is not increased in film thickness nor is it overexposed because the first flattening layer can be sufficiently separated from the ABS plane.
The thin-film magnetic head in claim 2 of the present invention is constituted by laminating a lower shielding layer, a read gap layer holding an MR magnetosensitive element in an ABS plane, a common pole layer serving as an upper shielding layer and a lower pole layer, and a write gap layer in order on an insulating substrate, then laminating a first flattening layer, a coil pattern layer, and a second flattening layer in order on the write gap layer excluding the vicinity of the ABS plane, and then forming at least an upper pole layer on the write gap layer nearby the ABS plane. Moreover, a concave portion is formed on the common pole layer at a position separated from the ABS plane, the concave portion is filled with a nonmagnetic body, and the gap depth between the upper pole layer and the lower pole layer is determined by the concave portion. That is, the thin-film magnetic head in claim 2 is an MR-inductive composite-type thin-filmmagnetic head obtained by combining an MR reproducing head with an inductive recording head.
The thin-film magnetic heads of claims 3 to 29 are constituted by restricting some components of the thin-film magnetic head of claim 1 or 2. The magnetic storage apparatus of claim 14 uses the thin-film magnetic head in claim 1 or 2.